Doped polysilanes, compositions containing the same, methods for making the same, and films formed therefrom

ABSTRACT

Doped polysilanes, inks containing the same, and methods for their preparation and use are disclosed. The doped polysilane generally has the formula H-[A a H b (DR x ) m ] q -[(A c H d R 1   e ) n ] p —H, where each instance of A is independently Si or Ge, and D is B, P, As or Sb. In preferred embodiments, R is H, -A f H f+1 R 2   f , alkyl, aryl or substituted aryl, and R 1  is independently H, halogen, aryl or substituted aryl. In one aspect, the method of making a doped poly(aryl)silane generally includes the steps of combining a doped silane of the formula A a H b+2 (DR x ) m  (optionally further including a silane of the formula A c H d+2 R 1   e ) with a catalyst of the formula R 4   w R 5   y MX z  (or an immobilized derivative thereof) to form a doped poly(aryl)silane, then removing the metal M. In another aspect, the method of making a doped polysilane includes the steps of halogenating a doped polyarylsilane, and reducing the doped halopolysilane with a metal hydride to form the doped polysilane. The synthesis of semiconductor inks via dehydrocoupling of doped silanes and/or germanes allows for tuning of the ink properties (e.g., viscosity, boiling point, surface tension and dopant level or concentration) and for deposition of doped silicon films or islands by spincoating, inkjetting, dropcasting, etc., with or without the use of UV irradiation.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/617,562, filed Oct. 8, 2004, which is incorporated herein byreference in its entirety. Furthermore, this application may be relatedto U.S. application Ser. No. 11/246,014, filed Oct. 6, 2005, which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

The present invention generally relates to the field of dopedpolysilanes and methods of making the same. More specifically,embodiments of the present invention pertain to polysilane compoundscontaining dopant atoms, compositions containing the same, and methodsfor making and using the same.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to doped polysilanes, dopedpolysilane ink compositions, methods for making the same and methods ofmaking an electrically active, semiconducting film using the same. Thedoped polysilanes generally have the formulaH-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹ _(e))_(n)]_(p)—H, whereeach instance of A is independently Si or Ge; D is B, P, As or Sb; eachinstance of R is independently H, -A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R²_(f)— (where R² is H, halogen, aryl or substituted aryl), alkyl,alkylene, aralkyl, substituted aralkyl, halogen, aryl, arylene orsubstituted aryl, and when an instance of x=2, the two R groups may forma ring together with D; q is at least 1, but q≧2 when p=0; each of the qinstances of a is independently at least 1; each of the q instances of bis independently an integer of from 1 to 2a; each of the q instances ofm is an integer of from 1 to a; each of the q*m instances of x isindependently 1 or 2; each instance of R¹ is independently H,-A_(f)H_(f+1)R² _(f), halogen, aryl or substituted aryl; each of the pinstances of n is independently at least 1; each of the p*n instances ofc is independently an integer of at least 1; each of the p*n instancesof d is independently an integer of from c to 2c; each of the p*ninstances of e is independently an integer of from 0 to c; and the sumof the p instances of n*c≧4 when q=1. In preferred embodiments, R is H,-A_(f)H_(f+1)R² _(f), alkyl, aryl or substituted aryl, and R¹ isindependently H, halogen, aryl or substituted aryl. In general, thenumber of silicon and/or germanium atoms in the polysilane may bedetermined according to the number average molecular weight (Mn) of thepolysilane. The compositions generally comprise the doped polysilanecompound (particularly the doped polysilanes in which R═H, C₁-C₆ alkyl,phenyl or -A_(f)H_(2f+1)) and a solvent in which the doped polysilane issoluble.

In one aspect, the method of making a doped poly(aryl)silane generallyincludes the steps of mixing or combining a doped silane compound theformula A_(a)H_(b+2)(DR_(x))_(m) (optionally further including a silanecompound of the formula A_(c)H_(d+2)R¹ _(e)) with a catalyst of theformula R⁴ _(w)R⁵ _(y)MX_(z) (or an immobilized derivative thereof) toform a doped poly(aryl)silane of the formulaH-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹ _(e))_(n)]_(p)—H, thenremoving the metal M. In the doped silane and poly(aryl)silane, eachinstance of A is independently Si or Ge; D is B, P, As or Sb; eachinstance of R is independently H, -A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R²_(f)— (where R² is H, halogen, aryl or substituted aryl), alkyl,alkylene, aralkyl, substituted aralkyl, halogen, aryl, arylene orsubstituted aryl, and when an instance of x=2, the two R groups may forma ring together with D; q is at least 1, but q≧2 when p=0; each of the qinstances of a is independently at least 1; each of the q instances of bis independently an integer of from 1 to 2a; each of the q instances ofm is an integer of from 1 to a; each of the q*m instances of x isindependently 1 or 2; each instance of R¹ is independently H,-A_(f)H_(f+1)R² _(f), halogen, aryl or substituted aryl; each of the pinstances of n is independently at least 1; each of the p*n instances ofc is independently an integer of at least 1; each of the p*n instancesof d is independently an integer of from c to 2c; each of the p*ninstances of e is independently an integer of from 0 to c; and the sumof the p instances of n*c≧4 when q=1. In the catalyst, M is a metalselected from the group consisting of Ti, Zr and Hf, x=1 or 2, y=1, 2 or3, z=0, 1 or 2, 3≧(x+y+z)≧8, each of the w instances of R⁴ isindependently a substituted or non-substituted cyclopentadienyl,indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy,hydrocarbylamino, or hydrocarbylsulfido ligand; each of the y instancesof R⁵ is independently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl,(per)alkylsilyl, germyl, (per)alkylgermyl, hydride, phosphine, amine,sulfide, carbon monoxide, nitryl, or isonitryl ligand, and X is ahalogen.

In another aspect, the method of making a doped polysilane includes thesteps of halogenating a doped polyarylsilane made by the catalyticdehydrocoupling reaction step (a) described above, and reducing thedoped halopolysilane with a metal hydride to form the doped polysilane.

The present invention is directed towards the synthesis of semiconductorinks via dehydrocoupling of doped (aryl)silanes and/or -germanes. Suchsynthesis allows for tuning of the ink properties (e.g., viscosity,boiling point, surface tension dopant level or concentration, etc.) andfor deposition of doped silicon films or islands by spincoating,inkjetting, dropcasting, etc., with or without the use of UVirradiation. Thus, the invention further relates to a method of makingor forming a doped or electrically active semiconductor film from thepresent ink composition, comprising the steps of: (A) spin-coating orprinting the composition onto a substrate (optionally, with simultaneousor immediately subsequent UV irradiation); (B) heating the compositionsufficiently to form a doped, amorphous, hydrogenated semiconductor; and(C) annealing and/or irradiating the doped, amorphous, hydrogenatedsemiconductor sufficiently to at least partially crystallize, reduce ahydrogen content of, and/or electrically activate the dopant in thedoped, amorphous, hydrogenated semiconductor, and thus form the doped orelectrically active semiconductor film.

These and other advantages of the present invention will become readilyapparent from the detailed description of preferred embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an approach for the synthesis of dopedpolysilanes from doped silanes by catalytic dehydrocoupling.

FIG. 2 is a diagram showing an approach for the synthesis of dopedpolysilanes from doped cyclosilanes by catalytic dehydrocoupling, inwhich units of doped and undoped silanes are identified by q and np,respectively, in the general formula.

FIG. 3 is a diagram showing an approach for the synthesis of dopedpolysilanes from doped silanes and arylsilane monomers by catalyticdehydrocoupling, halogenation, and reduction.

FIG. 4 is a diagram showing an alternative approach for the synthesis ofdoped polysilanes from an arylsilane monomer and a doped silane bycatalytic dehydrocoupling, halogenation, and reduction.

FIG. 5 is a diagram showing an approach for the synthesis of dopedpolycyclosilanes from a doped cyclosilane by catalytic dehydrocoupling.

FIG. 6 is a diagram showing an approach for the synthesis of dopedpolysilanes from arylsilane and doped silane monomers by catalyticdehydrocoupling, halogenation, and reduction.

FIG. 7 is a diagram showing an approach for the synthesis of dopedpoly(cyclo)silanes from arylsilane monomers and doped cyclosilanes bycatalytic dehydrocoupling, halogenation, and reduction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be readilyapparent to one skilled in the art that the present invention may bepracticed without these specific details. In other instances, well-knownmethods, procedures, components, and circuits have not been described indetail so as not to unnecessarily obscure aspects of the presentinvention.

For the sake of convenience and simplicity, the terms “C_(a)-C_(b)alkyl,” “C_(a)-C_(b) alkoxy,” etc., shall refer to both branched andunbranched moieties, to the extent the range from a to b covers 3 ormore carbon atoms. Unless otherwise indicated, the terms “arene,”“aryl,” and “ar-” refer to both mono- and polycyclic aromatic speciesthat may be unsubstituted or substituted with one or more conventionalsubstituents, to the extent possible and/or applicable. The prefixes“(per)alkyl” and “(per)hydro” refer to a group having from one to all ofits bonding sites substituted with alkyl groups or hydrogen atoms,respectively (e.g., “(per)alkylsilyl” refers to a silyl group of n atomshaving from 1 to 2n+1 alkyl groups bound thereto). The terms “silane,”“polysilane” and “(cyclo)silane” may be used interchangeably herein, andunless expressly indicated otherwise, these terms individually refer toa compound or mixture of compounds that consists essentially of (1)silicon and/or germanium and (2) hydrogen. The terms “arylsilane,”“polyarylsilane” and “aryl(cyclo)silane” may be used interchangeablyherein, and unless expressly indicated otherwise, these terms refer to acompound or mixture of compounds that contains or consists essentiallyof units having a silicon and/or germanium atom, a hydrogen atom boundthereto, and an aryl group bound thereto, where the aryl group may besubstituted by a conventional hydrocarbon, silane or germanesubstituent. The term “(aryl)silane” refers to a silane, polysilane orcyclosilane that may or may not contain an aryl or substituted arylgroup bound thereto. The terms “doped,” “dopant” and grammaticalvariations thereof may be used interchangeably herein, and unlessexpressly indicated otherwise, these terms refer to a species, group ormolecule containing a dopant atom such as B, P, As or Sb having acovalent bond to one or more conventional semiconductor element atoms(e.g., silicon and/or germanium). The prefix “(cyclo)-” generally refersto a compound or mixture of compounds that may contain a cyclic ring,and the prefix “cyclo-” or “c-” generally refers to a compound ormixture of compounds that contain one or more cyclic rings. For the sakeof briefness, the terms “halo-,” “halide” and grammatical derivationsthereof may describe halogens as defined in the Periodic Table ofElements (F, Cl, Br, and I) and halogen-like species (e.g., that formstable monovalent anions) such as methanesulfonate (OMs),trifluoromethanesulfonate (OTf, toluenesulfonate (OTs), etc. Also, theterms “isolating” and “purifying” (and grammatical variations thereof)may be used interchangeably herein, but these terms are intended to havetheir art-recognized meanings, unless indicated otherwise.

The present invention concerns a doped polysilane, a “liquid silicon”ink composition containing the doped polysilane, methods forsynthesizing the doped polysilane and for making the ink composition,and methods of using the doped polysilane and/or ink composition to makean electrically active semiconductor film. In general, the polysilanehas the formula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹_(e))_(n)]_(p)—H, where each instance of A is independently Si or Ge; Dis B, P, As or Sb; each instance of R is independently H,-A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R² _(f)— (where R² is H, halogen,aryl or substituted aryl), alkyl, alkylene, aralkyl, substitutedaralkyl, halogen, aryl, arylene or substituted aryl, and when aninstance of x=2, the two R groups may form a ring together with D; q isat least 1, but q≧2 when p=0; each of the q instances of a isindependently at least 1; each of the q instances of b is independentlyan integer of from 1 to 2a; each of the q instances of m is an integerof from 1 to a; each of the q*m instances of x is independently 1 or 2;each instance of R¹ is independently H, -A_(f)H_(f+1)R² _(f), halogen,aryl or substituted aryl; each of the p instances of n is independentlyat least 1; each of the p*n instances of c is independently an integerof at least 1; each of the p*n instances of d is independently aninteger of from c to 2c; each of the p*n instances of e is independentlyan integer of from 0 to c; and the sum of the p instances of n*c≧4 whenq=1. The composition generally comprises the polysilane compound(preferably where R and R¹ are H) and a solvent in which the polysilaneis soluble.

Even further aspects of the invention concern methods of making apolysilane generally comprising the steps of (a) mixing or combining adoped silane compound the formula A_(a)H_(b+2)(DR_(x))_(m) (optionallyfurther including a silane compound of the formula A_(c)H_(d+2)R¹ _(e))with a catalyst of the formula R⁴ _(w)R⁵ _(y)MX_(z) (or an immobilizedderivative thereof, or which can be synthesized in situ fromcorresponding precursors) to form a doped poly(aryl)silane of theformula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹ _(e))_(n)]_(p)—H,then removing the metal (i.e., in the catalyst) from the dopedpoly(aryl)silane. In the doped silane and poly(aryl)silane, eachinstance of A is independently Si or Ge; D is B, P, As or Sb; eachinstance of R is independently H, -A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R²_(f)-(where R² is H, halogen, aryl or substituted aryl), alkyl,alkylene, aralkyl, substituted aralkyl, halogen, aryl, arylene orsubstituted aryl, and when an instance of x=2, the two R groups may forma ring together with D; q is at least 1, but q≧2 when p=0; each of the qinstances of a is independently at least 1; each of the q instances of bis independently an integer of from 1 to 2a; each of the q instances ofm is an integer of from 1 to a; each of the q*m instances of x isindependently 1 or 2; each instance of R¹ is independently H,-A_(f)H_(f+1)R² _(f), halogen, aryl or substituted aryl; each of the pinstances of n is independently at least 1; each of the p*n instances ofc is independently an integer of at least 1; each of the p*n instancesof d is independently an integer of from c to 2c; each of the p*ninstances of e is independently an integer of from 0 to c; and the sumof the p instances of n*c≧4 when q=1. In the catalyst, M is a metalselected from the group consisting of Ti, Zr and Hf, w=1 or 2, y=1, 2 or3, z=0, 1 or 2, 3≧(x+y+z)≧8, each of the w instances of R⁴ isindependently a substituted or non-substituted cyclopentadienyl,indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy,hydrocarbylamino, or hydrocarbylsulfido ligand; each of the y instancesof R⁵ is independently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl,(per)alkylsilyl, germyl, (per)alkylgermyl, hydride, phosphine, amine,sulfide, carbon monoxide, nitryl, or isonitryl ligand, and X is ahalogen.

Alternatively, the method may first form a doped polyarylsilane bymixing or combining the doped silane compound the formulaA_(a)H_(b+2)(DR_(x))_(m) and the silane compound of the formulaA_(c)H_(d+2)R¹ _(e) (in which at least one instance of R¹ is aryl) withthe catalyst in accordance with step (a), then perform the steps of (b′)reacting the doped polyarylsilane with (i) a halogen source and(optionally) a Lewis acid, or (ii) trifluoromethanesulfonic acid (HOTf),to form a doped halopolysilane; and (c′) reducing the dopedhalopolysilane with a metal hydride to form a doped polysilane of theformula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c+g)H_(d+h))_(n)]_(p)—H,where g is the number of A atoms in the instances of R¹ where R¹ is-A_(f)H_(f+1)R² _(f), and h is a number of from e to [2(c+g)−h].

The invention further relates to a method of making or forming a dopedor electrically active semiconductor film from the present inkcomposition, comprising the steps of: (A) spin-coating or printing thecomposition onto a substrate (optionally, with simultaneous orimmediately subsequent UV irradiation); (B) heating the compositionsufficiently to form a doped, amorphous, hydrogenated semiconductor; and(C) annealing and/or irradiating the doped, amorphous, hydrogenatedsemiconductor sufficiently to at least partially crystallize, reduce ahydrogen content of and/or electrically activate the dopant in thedoped, amorphous, hydrogenated semiconductor, and thus form the doped orelectrically active semiconductor film.

Doped poly- and oligo-hydrosilane and -hydrogermane semiconductor inkscan be synthesized by dehydrocoupling of silyl- and/or germylphosphines(e.g., PH_(j)R_(3-j), where j is 0, 1 or 2, at least one R is-A_(f)H_(f+1)R² _(f) or at least two R groups together are -A_(f)H_(f)R²_(f)-) or silyl- and/or germylboranes (e.g., BH_(j)R_(3-j), where j is0, 1 or 2, at least one R is -A_(f)H_(f+1)R² _(f) or at least two Rgroups together are -A_(f)H_(f)R² _(f)-), optionally withperhydrosilanes and perhydrogermanes (linear, branched, cyclo-, caged,poly-, or oligosilanes and/or -germanes), or by dehydrocoupling ofarylhydrosilanes and arylhydrogermanes with such silyl- and/orgermylphosphines or silyl- and/or germylboranes, followed byhalogenative cleavage of the aryl groups and metal hydride reduction toyield doped perhydrosilanes and perhydrogermanes. The dopant level inthe ink compositions can be controlled by the ratio of dopant compound(e.g., the silyl- and/or germylphosphine or -borane) to perhydro- orarylhydrosilane or -germane in the dehydrocoupling reaction. The inksare used for production of amorphous or polycrystalline silicon,germanium, or silicon-germanium films by spincoating or inkjet printing,followed by curing at 400-500° C. and (optionally) laser-, heat-, ormetal-induced crystallization and/or dopant activation. Highly dopedfilms may be used to make contact layers in MOS capacitors, TFTs,diodes, etc. Lightly doped films may be used as semiconductor films inMOS capacitors, TFTs, diodes, etc.

The invention, in its various aspects, will be explained in greaterdetail below with regard to exemplary embodiments.

An Exemplary Doped Polysilane

In one aspect, the present invention relates to a doped polysilanesgenerally have the formula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹_(e))_(n)]_(p)—H, where each instance of A is independently Si or Ge; Dis B, P, As or Sb; each instance of R is independently H,-A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R² _(f)— (where R² is H, halogen,aryl or substituted aryl), alkyl, alkylene, aralkyl, substitutedaralkyl, halogen, aryl, arylene or substituted aryl, and when aninstance of x=2, the two R groups may form a ring together with D; q isat least 1, but q≧2 when p=0; each of the q instances of a isindependently at least 1; each of the q instances of b is independentlyan integer of from 1 to 2a; each of the q instances of m is an integerof from 1 to a; each of the q*m instances of x is independently 1 or 2;each instance of R¹ is independently H, -A_(f)H_(f+1)R² _(f), halogen,aryl or substituted aryl; each of the p instances of n is independentlyat least 1; each of the p*n instances of c is independently an integerof at least 1; each of the p*n instances of d is independently aninteger of from c to 2c; each of the p*n instances of e is independentlyan integer of from 0 to c; and the sum of the p instances of n*c≧4 whenq=1. In preferred embodiments, R is H, -A_(f)H_(f+1)R² _(f), alkyl, arylor substituted aryl, and R¹ is independently H, halogen, aryl orsubstituted aryl. In general, the number of silicon and/or germaniumatoms in the polysilane may be determined according to the numberaverage molecular weight (Mn) of the polysilane. Doped polysilaneshaving both cyclic blocks and linear/branched chains are contemplated.Thus, “p” and “q” may represent one or more blocks of substantiallylinear, branched or cyclic chains of silicon atoms in the polysilane.Thus, in general, the doped polysilane may comprise a doped homopolymerof repeating -(-A_(a)H_(2a−m)(DR_(x))_(m)—)—, -(-A_(a)H_(2a)(DR)_(m)—)—,-(-c-[A_(a)H_(2a−2)(DR)_(m)]—)— or -(c-[A_(a)H_(2a−2−m)]-(DR₂)_(m)—)—units, or a copolymer comprising one or more doped homopolymer blockswith one or more undoped blocks of repeating -(-AHR—)—,-(-A_(k)H_(2k)—)— and/or -(c-A_(m)H_(2m−2))— units, each of which mayinclude one or more such units in a given block.

In various preferred embodiments, D is B or P, and R is H,-A_(f)H_(f+1)R² _(f) (where f is an integer ≦6), alkyl, halogen, oraryl. More preferably, R may be H, -A_(f)H_(2f+1) where f is an integer≦4, C₁-C₆ alkyl, phenyl or tolyl. Even more preferably, R is C₁-C₄ alkyl(e.g., t-butyl).

In other embodiments of the present doped polysilane, a is at least 2(preferably at least 3), b is from a to 2a, and m is 1 or 2. Thus, a maybe an integer of from 2 to 6, and b may be (2a−2−m) when the“A_(a)H_(b)” moiety is cyclic and “DR.” is exocyclic, (2a−m) when the“A_(a)H_(b)” moiety is linear or branched and “DR.” is not in thepolymer chain or backbone (e.g., “DR.” is a substituent), (2a−2) whenthe “A_(a)H_(b)” moiety is cyclic and “DR_(x)” is endocyclic, or 2a whenthe “A_(a)H_(b)” moiety is linear or branched and “DR” is in the polymerchain or backbone (in this latter case, x=1). Thus, the doped polysilanemay have an average number of A atoms of at least 10 (preferably atleast 12, 15 or any other number greater than 10) according to or ascalculated from a number average molecular weight Mn of the dopedpolysilane. In some examples, the number of A atoms (e.g., Si atoms inthe chain or otherwise covalently bound thereto) may reach 50 or more.

A first exemplary doped polysilane has the formulaH-[A_(a)H_(b)(DR_(x))_(m)]_(q)—H (i.e., where p=0), where each instanceof A is independently Si or Ge; each instance of R is independently H,halogen, alkyl, aryl, substituted aryl, or -A_(f)H_(f+1)R² _(f) (whereR² is H, aryl or substituted aryl); and (q*[a+x*f])≧10. In general, thepolysilane has a linear structure (i.e., where the polymer chainconsists essentially of A atoms or a combination of A and D atoms), butbranched analogs (e.g., where R is -A_(b)H_(b+1)R¹ _(b)) are possible.Generally, such branched analogs will be present in a mixture with oneor more linear polysilanes. In general, the sum of the q instances of (aplus the x instances of f), or the q instances of (a plus the xinstances off) plus the p instances of n*c represent an average numberof silicon and/or germanium atoms in the product mixture, and in mostcases, that average number is less than or equal to 50 (preferably lessthan or equal to 25 or 30). For example, when the polysilane is linear,the average number of A atoms (or A and D atoms)≦50. However, undertypical conditions and/or using certain known catalysts and/or monomers,the average number of A atoms (or A and D atoms) is more typically ≦25or 30.

In certain embodiments of the present doped polysilane, p and q are atleast 1, n*p≧4 (e.g., n*p has an average value for a givendehydrocoupling reaction product mixture of at least 10), R¹ is phenyl,tolyl, Cl or H (preferably H), and/or A is Si. However, in otherembodiments, at least one A is Ge. In such an embodiment, the dopedpolygermasilane is essentially a random and/or statistical mixture ofdoped polysilanes, polygermanes and polygermasilanes containing aproportion or ratio of germanium-to-silicon atoms that substantiallycorresponds to the proportion or ratio of the germanium atoms to siliconatoms in the mixture of monomeric starting materials, as may be morefully explained herein.

The structure and nature of the present poly(aryl)silanes andpoly(halo)silanes may be better understood with reference to someexemplary methods for their synthesis.

An Exemplary Method of Making Doped Poly(aryl)silanes

In general, doped oligo- and polyhydrosilane and -hydrogermane compoundsfor semiconductor inks can be synthesized by dehydrocoupling ofhydrosilanes and/or hydrogermanes containing dopant atoms (e.g., whereand A=Si or Ge), to form linear, branched, cyclic, and/orheteropolysilanes and/or heteropolygermanes, and removing the catalystmetal from the doped poly(aryl)silane. Such metal removal may comprisecontacting the doped poly(aryl)silane with an adsorbent sufficiently toremove the metal, and optionally, washing the doped poly(aryl)silanewith an aqueous washing composition. This aspect of the inventionfocuses on dehydrocoupling of doped hydrosilanes and/or dopedhydrogermanes (e.g., compounds as small as D(AH₃)₃, where D is aconventional semiconductor dopant atom and A=Si or Ge).

Dehydrocoupling of arylhydrosilanes using titanium (Ti), zirconium (Zr),hafnium (Hf), neodymium (Nd) and uranium (U) catalysts is known (see,e.g., T. D. Tilley, Acc. Chem. Res. 1993, vol. 26, pp. 22-29; V. K.Dioumaev and J. F. Harrod, J. Organomet. Chem. vol. 521 [1996], pp.133-143; and Q. Wang and J. Y. Carey, Can. J. Chem. vol. 78 [2000], pp.1434-1440). In part, the present invention relates to use of thisapproach to synthesize novel doped polyarylhydrosilanes, -germanesand/or -silagermanes, and to an improved method for synthesizing dopedpolyarylhydrosilanes, -germanes and/or -silagermanes that eliminates themetal catalyst to a significantly greater degree than alternativeapproaches, thereby significantly improving the stability ofsubsequently-produced polyhydrosilanes, -germanes and/or -sila-germanes.

Thus, in one aspect, the present invention relates to a method of makinga doped poly(aryl)silane, generally including the steps of mixing orcombining a doped silane compound the formula A_(a)H_(b+2)(DR_(x))_(m)(optionally further including a silane compound of the formulaA_(c)H_(d+2)R¹ _(e)) with a catalyst of the formula R⁴ _(w)R⁵ _(y)MX_(z)(or an immobilized derivative thereof, or which can be synthesized insitu from corresponding precursors) to form a doped poly(aryl)silane ofthe formula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹_(e))_(n)]_(p)—H, then removing the metal (i.e., in the catalyst) fromthe doped poly(aryl)silane. Doped silanes of the formulaA_(a)H_(b+2)(DR_(x))_(m) (and/or examples thereof) are or may begenerally disclosed in one or more of U.S. patent application Ser. Nos.10/949,013, 10/950,373 and 10/956,714, respectively filed on Sep. 24,2004, Sep. 24, 2004, and Oct. 1, 2004, the relevant portions of whichare incorporated herein by reference.

In the doped silane and poly(aryl)silane, each instance of A isindependently Si or Ge; D is B, P, As or Sb; each instance of R isindependently H, -A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R² _(f)— (where R²is H, halogen, aryl or substituted aryl), alkyl, alkylene, aralkyl,substituted aralkyl, halogen, aryl, arylene or substituted aryl, andwhen an instance of x=2, the two R groups may form a ring together withD; q is at least 1, but q≧2 when p=0; each of the q instances of a isindependently at least 1; each of the q instances of b is independentlyan integer of from 1 to 2a; each of the q instances of m is an integerof from 1 to a; each of the q*m instances of x is independently 1 or 2;each instance of R¹ is independently H, -A_(f)H_(f+1)R² _(f), halogen,aryl or substituted aryl; each of the p instances of n is independentlyat least 1; each of the p*n instances of c is independently an integerof at least 1; each of the p*n instances of d is independently aninteger of from c to 2c; each of the p*n instances of e is independentlyan integer of from 0 to c; and the sum of the p instances of n*c≧4 whenq=1. In the catalyst, M is a metal selected from the group consisting ofTi, Zr and Hf, w=1 or 2, y=1, 2 or 3, z=0, 1 or 2, 3≦(x+y+z)≦8, each ofthe w instances of R⁴ is independently a substituted or non-substitutedcyclopentadienyl, indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, or hydrocarbylsulfido ligand; each ofthe y instances of R⁵ is independently a substituted or non-substitutedhydrocarbyl, hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido,silyl, (per)alkylsilyl, germyl, (per)alkylgermyl, hydride, phosphine,amine, sulfide, carbon monoxide, nitryl, or isonitryl ligand, and X is ahalogen.

Preferably, the metal M in the dehydrocoupling catalyst is Zr or Hf.These metals tend to provide a sufficient balance betweendehydrocoupling rate or activity, doped poly(aryl)silane molecularweight and content of (doped) cyclosilane by-products (e.g., Hfgenerally produces a higher proportion of linear polysilane productsthan Zr). In various embodiments, w is 2 and R⁴ is cyclopentadienyl(Cp), permethyl-cyclopentadienyl (Cp*), indenyl or fluorenyl (Fl).Having at least one bulky or substituted cyclopentadienyl ligand (e.g.,Cp*, indenyl or fluorenyl) tends to promote dehydrocoupling by reducinga tendency of the catalyst to dimerize, but the catalyst is not at allrequired to have such a ligand. Also, in various embodiments, y is 2 andR⁵ in the dehydrocoupling catalyst is H, C₁-C₆ alkyl, C₆-C₁₂ aryl, SiR²₃, or Si(SiR² ₃)₃, where R² is H or C₁-C₄ alkyl. Such ligands arebelieved to promote metathesis of Si—H or Ge—H bonds in the startingsilane compound.

In general, to remove the metal from the doped poly(aryl)silane, asolution of the doped poly(aryl)silane in a suitable organic solvent(typically the washed doped poly[aryl]silane) is contacted with theadsorbent for a length of time sufficient for the adsorbent to adsorbthe metal from the catalyst. The adsorbent generally comprises achromatography gel or finely divided silicon and/or aluminum oxide thatis substantially unreactive with the polyarylsilane. Examples ofsuitable adsorbents include silica gel, alumina, FLUORISIL, and CELITE.In one embodiment, such contacting comprises passing the dopedpoly(aryl)silane through a column packed with the adsorbent.Alternatively, a solution of the doped poly(aryl)silane may be mixedwith the adsorbent for a length of time sufficient for the adsorbent toadsorb the metal/catalyst from the solution. The adsorbent is generallyremoved from the adsorption mixture by conventional filtration.Alternatively, the metal may be removed by adding an inactivating ligand(somewhat surprisingly, such as a trialkyl- or triarylphosphine), thenremoving the inactivated catalyst by a conventional process (e.g.,precipitating one of the doped polysilane and the inactivated catalystwith an appropriate solvent, filtering and optionally removing thesolvent; by crystallization or recrystallization, by vacuum distillationof the doped polysilane, etc.)

Generally, some doped polysilanes may have A-D bonds (e.g., Si—P bonds)that may be sensitive to hydrolysis. As a result, washing the dopedpoly(aryl)silane is optional, and should be employed only when the dopedpoly(aryl)silane does not contain easily hydrolyzable A-D bonds. Thewashing composition may comprise deionized water or dilute aqueous acid.For example, the aqueous acids suitable for use in the present methodgenerally include the mineral acids and their equivalents, such ashydrochloric acid, hydrobromic acid, trifluoroacetic acid, andtrifluoromethanesulfonic acid. Preferably, the aqueous acid compriseshydrochloric acid. The dilution factor for the washing composition maybe from 1:1 to 1:1000 (concentrated mineral acid to water), generally byvolume. For example, the dilute aqueous acid may comprise from 0.1 to 10vol. % (e.g., from 1 to 5 vol. %) of conc. HCl in deionized water. Inone implementation, doped poly(aryl)silane washing comprises washing thedoped poly(aryl)silane one or more times with dilute aqueous acid,followed by washing the acid-washed doped poly(aryl)silane one or moretimes with water.

Referring now to FIG. 1, in a first exemplary embodiment of the presentmethod, a linear or branched doped silane compound of the formulaA_(a)H_(2a+1)DR₂ (e.g., (H₃Si)₃Si—PR₂ 10) may be catalyticallydehydrocoupled (or dehydrogenatively metathesized) using a Group IVBtransition metal catalyst, such as Cp₂Zr(t-Bu)₂, generated in situ fromCp₂ZrCl₂ and about 2 mole equivalents of t-butyl lithium, to formpoly(H₂Si—Si(SiH₃)(PR₂)—SiH₂) 10n. Thus, in preferred implementations ofthis embodiment, A is Si, a is 4 and/or b is (2a−m). However, R may beH, alkyl, aryl, or A_(f)H_(2f+1), and both R groups taken together maybe alkylene (e.g., —PR₂ is -c-P(CH₂)₄), arylene (e.g., —PR₂ is-c-P(α,α′-diphenylene)), or silylene (e.g., —PR₂ is -c-P(SiH₂)₄,-c-P(SiPh₂)₄, or -c-P(SiMe₂)₄). Preferably, R is H, phenyl,-A_(f)H_(2f+1) (where f is an integer from 1 to 4), or C₁-C₆ alkyl(e.g., isopropyl or t-butyl).

Where R is -A_(f)H_(2f+1), it is likely that a significant proportion ofcyclic and/or caged products are formed. For example, dehydrocoupling of(H₃Si)₃Si—PR₂ 10 may form a relatively small proportion of cyclic dimer[(H₂Si)₂(Si—PR₂)]₂ (not shown). Although the doped polysilanes may beseparated and/or isolated from the cyclic dimer or other relatively lowmolecular weight compounds, the relatively low molecular weight cycliccompounds generally do not affect subsequent steps in the synthesis ofdoped polysilanes.

The dehydrocoupling reaction evolves hydrogen gas, and thus, tends to beirreversible if the hydrogen gas is removed from the dehydrocouplingreaction vessel. Generally, the polymerization/dehydrocoupling reactiontime is from a few hours (e.g., 3, 4, 6 or more hours) to a few days(e.g., 3, 4 or 5 days). The reaction mixture may be formed by dropwiseaddition of the monomer to a solution of the catalyst, or by mixing thecatalyst directly with the monomer. In fact, neat solutions of dopedsilane/germane monomer and catalyst tend to provide higher molecularweights (e.g., number average molecular weights, or Mn) of dopedpoly(aryl)silanes. The reaction temperature may also be kept relativelylow (e.g., from about 0 to about 30° C.), generally to promote higherdoped poly(aryl)silane molecular weights and/or to reduce the amount ofrelatively low molecular weight and/or cyclic silane compounds. However,in some cases (e.g., when a sterically crowded catalyst and/or monomeris/are used), a higher temperature may be advantageous for increasingthe reaction rate.

As shown in FIG. 1, the dehydrocoupling catalyst Cp₂Zr(t-Bu)₂ may begenerated in situ from a zirconocene halide (e.g., Cp₂ZrCl₂) and analkyl, aryl or peralkylsilyl metal reagent (e.g., an alkyllithiumreagent such as t-butyllithium or PhMgBr, which can also be generated insitu in accordance with known techniques). Thus, dehydrogenativemetathesis may be conducted using a diaryl-, bis(peralkylsilyl)-,aryl(peralkylsilyl)-, dialkyl- or alkyl(peralkylsilyl) metallocenecatalyst such as Cp₂ZrPh₂. Further, the metal M, or one or more of the winstances of R⁴, y instances of R⁵ or z instances of X, can beindependently bound to a silica, alumina, or polymer surface renderingthe catalyst heterogeneous. The polymer is typically a hydrocarbonpolymer, such as polyethylene, polypropylene, polystyrene, apolyethylene-polypropylene or polyethylene-polystyrene copolymer, etc.

Alternative catalysts can include any conventional dehydrocouplingcatalyst, especially those containing a Group 4 element. For example, anHf analog of the Zr catalyst in FIG. 1 will generally reduce the amountof cyclic silane compounds produced. Also, as mentioned above,metallocene catalysts containing a relatively bulky ligand, such asCpCp*Zr(SiMe₃)Ph, may provide higher molecular weight polysilanes (e.g.,having a Mn as high as 5000 Daltons [i.e., 25-45 Si atoms]). Bycontrast, the Mn of a polyphenylsilane produced from PhSiH₃ usingCp₂ZrPh₂ is generally around 1200 Daltons (i.e., in a polymer of theformula H—(SiH₂)_(n)—H, n≈10-12). Use of a sterically crowded catalystlike CpCp*Zr(SiMe₃)Ph is expected to produce a higher viscosity dopedpolysilane ink composition.

Typical conditions for dehydrocoupling reaction include a temperature ofabout ambient or room temperature, a pressure of about atmosphericpressure (or about 1 atm) of inert gas under dynamic conditions (e.g.,in a reaction vessel having somewhat free gas out-flow, such as a gasbubbler, generally to allow escape of evolved hydrogen gas). The typicalcatalyst loading may be >1 mol (e.g., from 1 to 10 mol %, 2 to 5 mol %,or any range of values therein, relative to the molar quantity ofmonomer) for dehydrocoupling of doped silanes and doped germanes.

The adsorbing step in the present method is generally used to remove themetal of the catalyst (e.g., Zr in FIG. 1) from the doped polysilane10n. Conventional chromatography methods using gels, such as FLORISIL,and other gels like silica, alumina, and CELITE are generally suitable.Alternatively, the gel is added to a doped polysilane 10n solution andstirred (generally for a length of time sufficient to remove some orsubstantially all of the metal from the solution), then the gel isgenerally removed by filtration. Contacting a chromatography gel with asolution of the doped polysilane 10n can be substituted by simplypassing the solution of doped polysilane 10n through a thick pad of thegel.

The solvents used in the procedure are not limited. Cyclohexane,toluene, and diethyl ether are generally preferred, although any solventor mixture of solvents with relatively low boiling points (e.g., ≦100°C., ≦80° C., or ≦60° C.), compatible with doped poly(aryl)silanes, aresuitable.

FIG. 2 shows a second exemplary scheme illustrating dehydrocoupling ofdoped cyclosilane monomer c-(SiH₂)₅P—C(CH₃)₃ 20 (i.e., where R=t-butyl)and linear or branched (undoped) silane A_(a)H_(2a+2) 22 using thecatalyst of FIG. 1 to form a copolymer 24. In this copolymer, (np+q)≧3,5, or more. In the doped polysilane product 24, n and m may representthe sum of two or more blocks in the polymer (e.g., n=n₁+n₂+ . . .+n_(x)), and may generally represent a random and/or statistical mixturecorresponding to the molar ratio of c-(SiH₂)₅P—C(CH₃)₃ 20 to undopedsilane A_(a)H_(2a+2) 22 in the dehydrocoupling reaction mixture. Thus, mmay be anywhere from 1 to (n−1), but more typically, the molar ratio ofundoped silane (e.g., A_(a)H_(2a+2) 22) to doped silane monomer (e.g.,c-(SiH₂)₅P—C(CH₃)₃ 20) is anywhere from 1:1 to 20:1, and thus, n willtypically be an integer of from 1 to m. Furthermore, the resultingreaction mixtures may contain both heterocoupled polymers of doped(cyclic) silanes and undoped (linear/branched) silanes, and homocoupledpolymers of doped or undoped silanes.

Referring now to FIG. 5, in a further exemplary embodiment of thepresent method, a doped cyclosilane compound of the formulac-(A_(a)H_(2a))DR (e.g., c-(SiH₂)₄DR 210) may be catalyticallydehydrocoupled (or dehydrogenatively metathesized) using a Group IVBtransition metal catalyst, such as (Me₂SiFl₂)ZrBu₂, generated in situfrom (Me₂SiFl₂)ZrCl₂ and about 2 mole equivalents of butyllithium, toform poly(c-(Si₄H₆DR) 200. Doped silanes of the formulac-(A_(a)H_(2a))DR (and/or examples thereof) are or may be disclosed inU.S. patent application Ser. Nos. 10/950,373 and/or 10/956,714,respectively filed on Sep. 24, 2004, Sep. 24, 2004, and Oct. 1, 2004,the relevant portions of which are incorporated herein by reference.Thus, in such an approach, a may be 4 or 5, and b may be (2a−2). Inpreferred implementations of this embodiment, D is B or P, and R may bephenyl, -A/H_(2f+1) (where f is an integer from 1 to 4), or C₁-C₆ alkyl(e.g., t-butyl).

In the scheme of FIG. 5, where R is -A_(f)H_(2f+1), a proportion ofcyclic and/or caged products may be formed. For example, dehydrocouplingof c-(H₂Si)₄PSiH₃ 210 (i.e., where R═SiH₃) may form a relatively smallproportion of cyclic dimer c-(H₂Si)₄P—(SiH₂)₂-c-P(SiH₂)₄ (not shown).Although the doped polysilanes may be separated and/or isolated from thecyclic dimer or other relatively low molecular weight compounds, therelatively low molecular weight cyclic compounds generally do not affectsubsequent steps in the synthesis of doped polysilanes.

Another approach for making doped polysilanes by dehydrocoupling (butnot necessarily catalytically) involves direct coupling of a linear,branched or cyclic silane with a primary organophosphine or organoboranedopant:

In this case, the starting silane should be a poly(aryl)silane orpoly(cyclo)silane (e.g., containing at least 10 A atoms), but such apoly(aryl)silane may comprise the reaction mixture from the catalyticdehydrocoupling of an arylsilane monomer such as PhSiH₃, as disclosed inU.S. application Ser. No. 11/246,014, filed Oct. 6, 2005 (the relevantportions of which are incorporated herein by reference). When R is arelatively labile group (such as t-butyl), the carbon and/or hydrogencontent in an annealed and/or crystallized semiconductor film formedfrom the doped polysilane immediately above should be relatively smalland/or insignificant in terms of the desired electrical properties ofthe film.

An Exemplary Method of Making Doped Polysilanes

Cleavage of aryl groups bound to Si or Ge, and reduction of siliconand/or germanium halides and pseudo-halides are generally disclosed in,e.g., U.S. patent application Ser. Nos. 10/789,317, 10/949,013,10/950,373 and 10/956,714, respectively filed on Feb. 27, 2004, Sep. 24,2004, Sep. 24, 2004, and Oct. 1, 2004, the relevant portions of whichare incorporated herein by reference. Typically, and as shown in FIGS.3-4 and 6-7, this cleavage reaction is conducted with HCl and AlCl₃.However, as is also known, a conventional chlorination-based cleavagereaction can be substituted with HBr to obtain a polybromosilane, orwith TfOH to obtain a poly(trifluoromethanesulfonyl)silane. Thus, thepresent invention also relates to the combination of (1) catalyticdehydrocoupling as described above and (2) the cleavage and reductionprocesses described herein, to synthesize doped polyhydrosilanes,-germanes and/or -silagermanes.

Thus, in another aspect, the present invention concerns a method ofmaking a doped polysilane, comprising the steps of (a) combining ormixing a doped silane of the formula A_(a)H_(b+2)(DR_(x))_(m) and anarylsilane compound of the formula A_(c)H_(d+2)R¹ _(e) with a catalystof the formula R⁴ _(w)R⁵ _(y)MX_(z) (or an immobilized derivativethereof, or which may be synthesized in situ from correspondingprecursors) to form a doped polyarylsilane of the formulaH-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹ _(e))_(n)]_(p)—H, (b)reacting the doped polyarylsilane with (i) a halogen source and(optionally) a Lewis acid or (ii) trifluoromethanesulfonic acid (HOTf),to form a doped halopolysilane; and (c) reducing the dopedhalopolysilane with a metal hydride to form a doped polysilane of theformula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c+g)H_(d+h))_(n)]_(p)—H,where g is the number of A atoms in the instances of R¹ where R¹ is-A_(f)H_(f+1)R² _(f), and h is a number of from e to (e+2g). In thedoped silane and the doped polysilane, each instance of A isindependently Si or Ge; D is B, P, As or Sb; each instance of R isindependently H, -A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R² _(f)— (where R²is H, halogen, aryl or substituted aryl), alkyl, alkylene, aralkyl,substituted aralkyl, halogen, aryl, arylene or substituted aryl; andwhen an instance of x=2, the two R groups may form a ring together withD; q and p are each at least 1; each of the q instances of a isindependently at least 1; each of the q instances of b is independentlyan integer of from 1 to 2a; each of the q instances of m is an integerof from 1 to a; each of the q*m instances of x is independently 1 or 2;each instance of R¹ is independently H, -A_(f)H_(f+1)R² _(f), aryl orsubstituted aryl, but at least 1 instance of R¹ is aryl or substitutedaryl; each of the p instances of n is independently at least 1; each ofthe p*n instances of c is independently an integer of at least 1; eachof the p*n instances of d is independently an integer of from (c−1) to(2c−1); and each of the p*n instances of e is independently an integerof from 1 to c. In the catalyst, M is a metal selected from the groupconsisting of Ti, Zr and Hf, w=1 or 2, y=1, 2 or 3, z=0, 1 or 2,3≦(x+y+z)≦8, each of the w instances of R⁴ is independently asubstituted or non-substituted cyclopentadienyl, indenyl, fluorenyl,siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy, hydrocarbylamino, orhydrocarbylsulfido ligand; each of the y instances of R⁵ isindependently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl, germyl,hydride, phosphine, amine, sulfide, carbon monoxide, nitryl, orisonitryl ligand, and X is a halogen.

Generally, the method comprises combining a doped silane of the formulaA_(a)H_(b+2)(DR_(x))_(m) and an arylsilane compound of the formulaA_(c)H_(d+2)R¹ _(e) (e.g., AH₃R¹) with a catalyst of the formula R⁴_(w)R⁵ _(y)MX_(z) to form a doped polyarylsilane of the formulaH-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹ _(e))_(n)]_(p)—H. Dopedsilanes of the formula A_(a)H_(b+2)(DR_(x))_(m) are or may be disclosedin one or more of U.S. patent application Ser. Nos. 10/949,013,10/950,373 and 10/956,714, respectively filed on Sep. 24, 2004, Sep. 24,2004, and Oct. 1, 2004, the relevant portions of which are incorporatedherein by reference. Also, as described in copending U.S. applicationSer. No. 11/246,014, filed Oct. 6, 2005 (the relevant portions of whichare incorporated herein by reference), arylsilane compounds of theformula A_(k)H_(g)R^(1′) _(h) (particularly where k is an integer of atleast 2, g=[k+2], and h=k) are likely to be present in a dehydrocouplingreaction mixture containing an arylsilane compound of the formulaA_(c)H_(d+2)R¹ _(e) (particularly homocoupled oligomers or polymers ofthe silane of the formula AH₃R¹). As a result, the present methodcontemplates use of linear, branched or cyclic arylhydrosilanes of theformula A_(c)H_(d+2)R^(1′) _(e) for making doped polyarylsilanes.

Also, in certain embodiments, the method comprises reacting thepolyarylsilane with the halogen source and the Lewis acid, wherein theLewis acid comprises a compound of the formula M³ _(v)X² _(u), where M³comprises a member selected from the group consisting of transitionmetals and Group IIIA elements; v is 1 or 2; X² comprises a halogen; andu is any integer up to the number of ligand binding sites available onthe v instances of M³. In a preferred embodiment, M³ comprises Al, andX² is Cl or Br (e.g., Cl, as shown in FIGS. 3-4 and 6-7).

In further embodiments of the present method, the metal hydridecomprises a compound of the formula M¹ _(a′)M² _(b′)H_(c′)R⁶ _(d′),where M¹ and M² are independently first and second metals, each R⁶ inthe metal hydride compound is independently a ligand bound to at leastone of M¹ and M² by a covalent, ionic or coordination bond, at least oneof a′ and b′ is at least 1, c′ is at least 1, and d′ is 0 or any integerup to one less than the number of ligand binding sites available on the(a+b) instances of M¹ and M². In certain implementations, the metalhydride comprises a member of the group consisting of lithium aluminumhydride (LAH, as shown in FIGS. 1-2), calcium aluminum hydride, sodiumborohydride, aluminum hydride, gallium hydride, and aluminumborohydride.

Referring to FIGS. 3-4, the procedure for Lewis acid-catalyzedhalogenation (e.g., treatment or reaction of doped polyarylsilane 30 or120 (respectively formed by catalytic dehydrocoupling of (H₃Si)₃SiPHR 12and PhSiH₃ 25 [FIG. 3], or PhSiH₃ 25 and linear doped silane(H₂Si)₅(PR₂)₂ 110 [FIG. 4]) with HCl and AlCl₃ in an inert organicsolvent such as cyclohexane is largely as described in U.S. patentapplication Ser. No. 10/789,317. However, exemplary variations of theprocedure include a halogenation (e.g., chlorination) by bubbling HX gas(e.g., dry HCl) through a solution of doped polyarylsilane 30 or 120 anda Lewis acid for a length of time of from 30 min. to about 6 hours toform polychlorosilane 40 or 130, respectively, and reduction using ametal hydride reducing reagent (not limited to lithium aluminum hydride[LAH], although LAH as shown in FIGS. 3-4 is a preferred metal hydridereducing reagent) for a length of time of from about 1 hour, 2 hours or4 hours to about 8, 12, or 16 hours (e.g., overnight). Other exemplarymetal hydride reducing agents are disclosed in U.S. patent applicationSer. Nos. 10/789,317, 10/949,013, 10/950,373 and 10/956,714, therelevant portions of which are incorporated herein by reference. Also,the reagent addition sequence preferably comprises adding a solution ofmetal hydride (e.g., LAH) in an inert organic solvent (e.g., dry diethylether) to a stirred solution of doped polychlorosilane 40 or 130. Workupis generally as described in U.S. patent application Ser. Nos.10/789,317, 10/949,013, 10/950,373 and 10/956,714, the relevant portionsof which are incorporated herein by reference.

The starting material(s) and/or substrates generally include silicon andgermanium compounds of the general formula R¹AH₃ or R¹ ₂AH₂, where A isSi or Ge, and R¹ is aryl or substituted aryl. Use of tolylsilane(CH₃C₆H₄SiH₃) as a monomer instead of phenylsilane (PhSiH₃) may beadvantageous for subsequent steps in the doped polysilane synthesis.Tolylsilane (and oligomers thereof) are generally easier to chlorinate(e.g., cleave the C—Si bond with HCl and a Lewis acid such as AlCl₃),thereby presumably reducing aromatic impurities in any subsequentlysynthesized doped polysilane.

In further embodiments of the approach exemplified in FIGS. 3-4 and 6-7,A is independently Si or Ge, each polyarylsilane 30 or 120 may contain anumber of subblocks n₁-n_(x) and/or m₁-m_(y) where x and y areindependently an integer of from 2 to 12 (preferably from 2 to 8). Inaddition, linear and/or branched silanes of the general formulaA_(k)H_(2k+2) (where k is from 1 to 12, preferably from 5 to 10 [e.g.,for homogeneous synthesis] or from 1 to 4 [e.g., for heterogeneoussynthesis]) may be added to the dehydrocoupling reaction mixture to formtriblock arylpolysilanes, generally as described herein.

In another aspect, FIG. 6 shows a scheme for making capped,substantially linear doped oligo- and/or polysilanes, based on catalyticdehydrocoupling (e.g., dehydrocoupling of undoped [aryl]silanes and/or[aryl]germanes with sterically crowded, doped silanes and/or germanes).FIG. 6 shows an exemplary scheme illustrating dehydrocoupling ofphenylsilane (PhSiH₃) 25 with di-t-butyl(silylated)phosphine 310 to formcopolymer or linear/branched end-capped doped poly(phenylsilylene) 320.Generally, some di-capped polymer 325 will be formed as well. The numberof A atoms in the polymers 320 and 325 (e.g., the length of the siliconchain) can be controlled by the molar ratio of undoped monomer (e.g.,phenylsilane 25) to doped silane capping group. For example, a molarratio of from 4:1 to about 20:1 may give good results in terms of inkviscosity, dopant concentration, molecular weight (e.g., Mn) uniformity,etc. Linear or branched perhydrosilanes can be substituted for or addedto the undoped silane monomer, to provide a greater degree of branchingor to possibly increase the average number of silicon atoms in thepolymer/oligomer.

The capping effect of di-t-butyl(silylated)phosphine 310 may be mostadvantageous when a (i.e., the number of A atoms) is relatively small(e.g., 3 or less, such as SiH₃). Of course, it may not always bepossible to make di-t-butyl(silylated)phosphine 310, so other groupscontributing to steric crowding at the dopant atom may be substitutedfor one or both of the t-butyl groups (e.g., phenyl, tolyl, t-hexyl or3,3-dimethylbutyl, i-butyl or n-butyl). Such steric crowding may alsoreduce any rate-limiting effects the dopant atom may have on thedehydrocoupling reaction.

A Third Exemplary Method for Making Doped Oligo- and/or Polysilanes

In another aspect, the present invention concerns doped oligo- and/orpolysilanes containing both linear and cyclic portions and a method ofmaking the same, based on catalytic dehydrocoupling (e.g.,dehydrocoupling of [aryl]silanes and/or [aryl]germanes with cyclosilanesand/or cyclogermanes), such as the exemplary reaction scheme of FIG. 7.FIG. 7 shows an exemplary scheme illustrating dehydrocoupling ofphenylsilane (PhSiH₃) with cyclo-Si₄H₈PR 410 to form copolymer orlinear/branchedpoly(phenylsila)(cyclotetrasilylene[substituted]-phosphine) 420.Generally, the same dehydrocoupling catalyst (e.g.,bis[cyclopentadienyl]diphenylzirconium or [Fl₂SiMe₂]ZrBu₂, as shown inFIGS. 1-6) described above may be used for dehydrocoupling arylsilaneswith doped cyclosilanes. Linear or branched perhydrosilanes can besubstituted for or added to the undoped silane monomer, to provide agreater degree of branching or to possibly increase the average numberof silicon atoms in the polymer/oligomer. Also, cyclosilanes with anexocyclic silyl group (e.g., where R═SiH₃) are also contemplated for usein the invention.

An Exemplary Composition and/or Ink Containing a Doped Polysilane

A further aspect of the present invention relates to a composition,comprising the present doped polysilane and a solvent in which the dopedpolysilane is soluble. Preferably, the solvent is one that is easilyremoved (and/or substantially completely removable) from thecomposition, and may be selected from the group consisting of linearalkanes, cycloalkanes, polycycloalkanes, (cyclic) siloxanes andfluoroalkanes. The (cyclic) siloxane solvents are generally those thatare liquid at ambient temperatures (e.g., 15-30° C.), and may beselected from siloxanes of the formula (R₃Si)(OSiR₂)_(p)(OSiR₃) andcyclosiloxanes of the formula (SiR′₂O)_(q), where p is from 0 to 4, q isfrom 2 to 6 (preferably from 3 to 5), each R and R′ is independently H,C₁-C₆ alkyl, benzyl or phenyl substituted with from 0 to 3 C₁-C₄ alkylgroups (preferably R and R′ are methyl). The fluoroalkane may beselected from C₃-C₈ fluoroalkanes substituted with from 1 to (2m+2)fluorine atoms and that are liquid at ambient temperatures, where m isthe number of carbon atoms in the fluoroalkane. More preferably, thesolvent may be selected from the group consisting of C₆-C₁₂monocycloalkanes and C₁₀-C₁₄ di- or tricycloalkanes (e.g., decalin).Preferably, the solvent is a C₆-C₁₀ cycloalkane (e.g., cyclohexane,cycloheptane, cyclooctane, etc.).

In the present ink composition, the doped polysilane is present in anamount of from about 0.001 to about 50%, preferably 0.01 to about 20%(more preferably from about 0.05 to about 10%) by weight or by volume.The present ink composition may further comprise an undoped polysilanein an amount of from about 0.5 to about 50%, about 5 to about 30%, orabout 10 to about 20% by weight or by volume. Of course, when the dopedpolysilane (and, when present, any undoped polysilane) is in a liquidphase at room temperature, it may be used neat if its viscosity (and/orother physical and/or chemical properties) are suitable for printingand/or coating processes. Suitable ink formulations are disclosed inU.S. patent application Ser. Nos. 10/789,274, 10/789,317, 10/949,013,10/950,373 and 10/956,714, respectively filed on Feb. 27, 2004, Feb. 27,2004, Sep. 24, 2004, Sep. 24, 2004, and Oct. 1, 2004, the relevantportions of which are incorporated herein by reference.

An Exemplary Method for Making a Doped Semiconductor Film

A further aspect of the invention relates to a method of forming a dopedor electrically active semiconductor film from the present composition,comprising the steps of (A) spin-coating or printing the compositiononto a substrate (optionally, with simultaneous or immediatelysubsequent UV irradiation); (B) heating the composition sufficiently toform a doped, amorphous, hydrogenated semiconductor; and (C) annealingand/or irradiating the doped, amorphous, hydrogenated semiconductorsufficiently to at least partially crystallize, reduce a hydrogencontent of, and/or electrically activate the dopant in the doped,amorphous, hydrogenated semiconductor, and form the doped orelectrically active semiconductor film. Preferably, the method offorming a doped or electrically active semiconductor film comprisesprinting (e.g., inkjetting) the composition onto a substrate (e.g., aconventional silicon wafer, glass plate, ceramic plate or disc, plasticsheet or disc, metal foil, metal sheet or disc, or laminated or layeredcombination thereof, any of which may have an insulator layer such as anoxide layer thereon), and/or irradiating the doped, amorphous,hydrogenated semiconductor with a sufficient dose of laser radiation tocrystallize and/or electrically activate the doped, amorphous,hydrogenated semiconductor and form an electrically active semiconductorfilm.

In the present method, it may be advantageous to irradiate thecomposition during deposition onto the substrate. Generally, as long asthe ink composition is irradiated reasonably shortly after deposition(e.g., spincoating), it has a viscosity sufficient to form a film orlayer on the substrate that does not bead up, disproportionate orotherwise substantially adversely affect the uniformity of asubsequently formed semiconductor film. Such irradiation of a coatedand/or printed film prior to curing may provide further control of thefilm drying process, e.g., by increasing the viscosity of the inkcomposition after deposition. For example, the present composition(e.g., prior to deposition) may have a viscosity of from 2.5 to 20 cP, 3to 12 cP, or any range of values therein. Due to the potentialsensitivity of the present polysilanes to air, such deposition and(optional) irradiation should be conducted in an inert atmosphere.

Suitable methods for forming a semiconductor film are disclosed in U.S.patent application Ser. Nos. 10/789,274, 10/949,013, 11/084,448 and11/203,563, respectively filed on Feb. 27, 2004, Sep. 24, 2004, Mar. 18,2005 and Aug. 11, 2005, the relevant portions of which are incorporatedherein by reference. In the present case, the doped polysilane inkcomposition may further include a (cyclo)silane and/orhetero(cyclo)silane as described in U.S. patent application Ser. Nos.10/789,274, 10/949,013, 11/084,448 and 11/203,563. The first heatingand/or annealing step may comprise (i) “soft” curing the printed orcoated ink composition, generally at a temperature of ≦200° C., ≦150°C., ≦120° C. or any maximum temperature in that range, sufficiently toremove volatile components (e.g., solvent, volatile silane compounds,etc.) and/or to further polymerize the doped silane film, and (ii)“hard” curing the film, generally at a temperature of ≦600° C., ≦500°C., ≦450° C. or any maximum temperature in that range, sufficiently toform a doped, hydrogenated, amorphous silicon film. Due to the potentialsensitivity of the present polysilanes to air, such curing (e.g., “soft”and/or “hard” curing) should be conducted in an inert atmosphere.Generally, to obtain the most commercially valuable electrical activityand/or characteristics, the film is crystallized by heating in a furnaceor irradiating with a dose of laser radiation sufficient to partly orsubstantially completely crystallize the doped, hydrogenated, amorphoussilicon film (e.g., form a polycrystalline silicon film). The use oflaser radiation for crystallization advantageously includes a furtherannealing step to reduce the hydrogen content of the doped,hydrogenated, amorphous silicon film prior to laser irradiation.

Coating may comprise spin coating, inkjetting, dip-coating,spray-coating, slit coating, extrusion coating, or meniscus coating theink composition onto a substrate. Preferably, coating comprises spincoating. Printing may comprise inkjetting or gravure, flexographic,screen or offset printing the ink in locations on the substratecorresponding to active transistor regions. After drying and/or heatingthe printed/coated film to remove any solvents and/or cure the film, andoptionally irradiating the film (e.g., to fix the silanes to thesubstrate and/or to each other), the resulting semiconductor film/layergenerally has an amorphous morphology, and before further processing, itis generally annealed (e.g., to reduce the hydrogen content of thepolysilane) and crystallized (e.g., by heating or by laser irradiation;see, e.g., U.S. patent application Ser. Nos. 10/950,373 and 10/949,013,each of which was filed on Sep. 24, 2004, the relevant portions of whichare incorporated herein by reference). In many cases, suchcrystallization will also activate at least some of the dopant.

One may also induce crystallization (in addition to activating some orall of the dopant) using conventional metal-promoted(re)crystallization. Suitable metal-based crystallization promoters andprocesses for their use in crystallizing an amorphous semiconductor film(e.g., as formed from semiconductor nanoparticles containing Si and/orGe) may be disclosed in copending application Ser. No. 10/339,741, filedJan. 8, 2003 and entitled “Nanoparticles and Method for Making theSame”, the relevant portions of which are incorporated herein byreference.

CONCLUSION/SUMMARY

As described above, doped oligo- and polysilanes and -germanes suitablefor semiconductor inks can be synthesized by dehydrocoupling of silyl-and/or germylphosphines, or silyl- and/or germylboranes, optionally inthe presence of perhydrosilanes and perhydrogermanes. Alternatively,such doped oligo- and polysilanes and -germanes may be synthesized bydehydrocoupling of arylhydrosilanes and arylhydrogermanes with suchsilyl- and/or germyl-phosphines or -boranes, followed by halogenativecleavage of the aryl groups and metal hydride reduction to yield dopedperhydrosilanes and perhydrogermanes. Such synthesis allows for tuningof the ink properties (e.g., viscosity, boiling point, and surfacetension) and for deposition of silicon films or islands by spincoating,inkjetting, dropcasting, etc., with or without the use of UVirradiation. For example, the dopant level in the ink compositions canbe controlled by the ratio of dopant compound (e.g., the silyl- and/orgermylphosphine or -borane) to perhydro- or arylhydrosilane or -germanein the dehydrocouping reaction.

The inks can be used for production of amorphous and polycrystallinesilicon, germanium, or silicon-germanium films by spincoating or inkjetprinting, followed by curing at 400-500° C. and (optionally) laser-,heat-, or metal-induced crystallization (and/or dopant activation, whendopant is present; also see, e.g., U.S. application Ser. No. 11/246,014,filed concurrently herewith and incorporated herein by reference in itsentirety). Highly doped films may be used to make contact layers in MOScapacitors, TFTs, diodes, etc. Lightly doped films may be used assemiconductor films in MOS capacitors, TFTs, diodes, etc.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the claims appended hereto and theirequivalents.

1. A method of making a doped poly(aryl)silane, comprising: a) mixing adoped silane compound of the formula A_(a)H_(b+2)(DR_(x))_(m)(optionally further including a silane compound of the formulaA_(c)H_(d+2)R¹ _(e)) with a catalyst of the formula R⁴ _(w)R⁵ _(y)MX_(z)(or an immobilized derivative thereof) to form a doped poly(aryl)silaneof the formula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)hl_(d)R¹_(e))_(n)]_(p)—H, where each instance of A is independently Si or Ge; Dis B, P, As or Sb; each instance of R is independently H,-A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R² _(f)— (where R² is H, halogen,aryl or substituted aryl), alkyl, alkylene, aralkyl, substitutedaralkyl, halogen, aryl, arylene or substituted aryl, and when aninstance of x=2, the two R groups may form a ring together with D; q isat least 1, but q≧2 when p=0; each of the q instances of a isindependently at least 1; each of the q instances of b is independentlyan integer of from 1 to 2a; each of the q instances of m is an integerof from 1 to a; each of the q*m instances of x is independently 1 or 2;each instance of R¹ is independently H, -A_(f)H_(f+1)R² _(f), halogen,aryl or substituted aryl; each of the p instances of n is independentlyat least 1; each of the p*n instances of c is independently an integerof at least 1; each of the p*n instances of d is independently aninteger of from c to 2c; each of the p*n instances of e is independentlyan integer of from 0 to c; and the sum of the p instances of n*c≧4 whenq=1; M is a metal selected from the group consisting of Ti, Zr and Hf,w=1 or 2, y=1, 2 or 3, z=0, 1 or 2, 3 (x+y+z)≦8, each of the w instancesof R⁴ is independently a substituted or non-substitutedcyclopentadienyl, indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, or hydrocarbylsulfido ligand; each ofthe y instances of R⁵ is independently a substituted or non-substitutedhydrocarbyl, hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido,silyl, (per)alkylsilyl, germyl, (per)alkylgermyl, hydride, phosphine,amine, sulfide, carbon monoxide, nitrile, or isonitrile ligand, and X isa halogen; and b) removing said metal from said doped poly(aryl)silane.2. The method of claim 1, wherein a is from 2 to 6, and b is (2a−2-m),(2a−2), (2a−m), or 2a.
 3. The method of claim 1, wherein R is H,-A_(f)H_(2f+1) (where f is an integer≦4), or C₁-C₆ alkyl.
 4. The methodof claim 1, wherein the doped poly(aryl)silane has an average number ofA atoms of at least 10 according to or as calculated from a numberaverage molecular weight Mn of the doped polysilane.
 5. The method ofclaim 1, comprising mixing the doped silane compound of the formulaA_(a)H_(b+2)(DR_(x))_(m) with the silane compound of the formulaA_(c)H_(d+2)R¹ _(e) and a catalyst of the formula R⁴ _(w)R⁵ _(y)MX_(z),wherein p≧1, and the silane compound has the formula AH₃R¹.
 6. Themethod of claim 5, wherein R¹ is phenyl or tolyl.
 7. The method of claim1, further comprising washing said doped poly(aryl)silane with a washingcomposition comprising water.
 8. The method of claim 1, wherein saidremoving comprises contacting said doped poly(aryl)silane with anadsorbent sufficient to remove said metal from said dopedpoly(aryl)silane.
 9. The method of claim 1, wherein D is B or P.
 10. Themethod of claim 1, wherein R¹ is phenyl, tolyl, Cl or H; and n*p≧4. 11.The method of claim 1, wherein A is Si.
 12. The method of claim 1,wherein M is Zr or Hf.
 13. The method of claim 1, wherein R⁴ iscyclopentadienyl, permethylcyclo-pentadienyl, indenyl or fluorenyl. 14.The method of claim 1, wherein R⁵ is H, C₁-C₆ alkyl, C₆-C₁₂ aryl, SiR⁶₃, or Si(SiR⁶ ₃)₃, where R⁶ is H or C₁-C₄ alkyl.
 15. The method of claim1, wherein removing said metal from said doped poly(aryl)silanecomprises contacting said poly(aryl)silane with an adsorbent.
 16. Themethod of claim 15, wherein said adsorbent comprises a chromatographygel or finely divided silicon and/or aluminum oxide that issubstantially unreactive with said poly(aryl)silane.
 17. The method ofclaim 5, wherein A is Si.
 18. The method of claim 5, wherein D is P orB.
 19. A method of making a doped polysilane, comprising: a) mixing orcombining a doped silane compound of the formulaA_(a)H_(b+2)(DR_(x))_(m) and an arylsilane compound of the formulaA_(c)H_(d+2)R¹ _(e) with a catalyst of the formula R⁴ _(w)R⁵ _(y)MX_(z)(or an immobilized derivative thereof) to form a doped polyarylsilane ofthe formula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c)H_(d)R¹_(e))_(n)]_(p)—H, where each instance of A is independently Si or Ge; Dis B, P, As or Sb; each instance of R is independently H,-A_(f)H_(f+1)R² _(f) or -A_(f)H_(f)R² _(f)— (where R² is H, halogen,aryl or substituted aryl), alkyl, alkylene, aralkyl, substitutedaralkyl, halogen, aryl, arylene or substituted aryl, and when aninstance of x=2, the two R groups may form a ring together with D; q andp are each at least 1; each of the q instances of a is independently atleast 1; each of the q instances of b is independently an integer offrom 1 to 2a; each of the q instances of m is an integer of from 1 to a;each of the q*m instances of x is independently 1 or 2; each instance ofR¹ is independently H, -A_(f)H_(f+1)R² _(f), aryl or substituted aryl,but at least 1 instance of R¹ is aryl or substituted aryl; each of the pinstances of n is independently at least 1; each of the p*n instances ofc is independently an integer of at least 1; each of the p*n instancesof d is independently an integer of from (c−1) to (2c−1); each of thep*n instances of e is independently an integer of from 1 to c; M is ametal selected from the group consisting of Ti, Zr and Hf, w=1 or 2,y=1, 2 or 3, z=0, 1 or 2, 3 (x+y+z)≦8, each of the w instances of R⁴ isindependently a substituted or non-substituted cyclopentadienyl,indenyl, fluorenyl, siloxyl, germoxyl, hydrocarbyl, hydrocarbyloxy,hydrocarbylamino, or hydrocarbylsulfido ligand; each of the y instancesof R⁵ is independently a substituted or non-substituted hydrocarbyl,hydrocarbyloxy, hydrocarbylamino, hydrocarbylsulfido, silyl, germyl,hydride, phosphine, amine, sulfide, carbon monoxide, nitrile, orisonitrile ligand, and X is a halogen; b) reacting said dopedpolyarylsilane with (i) a halogen source and (optionally) a Lewis acidor (ii) trifluoromethanesulfonic acid (HOTf) to form a dopedpolyhalosilane; and c) reducing said doped polyhalosilane with a metalhydride to form a doped polysilane of the formulaH-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(A_(c+g)H_(d+h))_(n)]_(p)—H, where g isthe number of A atoms in the instances of R¹ where R¹ is -A_(f)H_(f+1)R²_(f), and h is a number of from e to (e+2g).
 20. The method of claim 19,comprising reacting said doped polyarylsilane with said halogen sourceand said Lewis acid, wherein said Lewis acid comprises a compound of theformula M³ _(v)X² _(u), where M³ comprises a member selected from thegroup consisting of transition metals and Group IIIA elements; v is 1 or2; X² comprises a halogen; and u is any integer up to the number ofligand binding sites available on the v instances of M³.
 21. The methodof claim 19, wherein said metal hydride comprises a compound of theformula M¹ _(a′)M² _(b′)H_(c′)R⁶ _(d′), where M¹ and M² areindependently first and second metals, each R⁶ in said metal hydridecompound is independently a ligand bound to at least one of M¹ and M² bya covalent, ionic or coordination bond, at least one of a′ and b′ is atleast 1, c′ is at least 1, and d′ is 0 or any integer up to one lessthan the number of ligand binding sites available on the (a+b) instancesof M¹ and M².
 22. The method of claim 19, wherein said silane compoundhas the formula AH₃R¹, and said reducing step forms a doped polysilaneof the formula H-[A_(a)H_(b)(DR_(x))_(m)]_(q)-[(AH₂)_(n)]_(p)—H.
 23. Themethod of claim 20, wherein said metal hydride comprises a member of thegroup consisting of lithium aluminum hydride, calcium aluminum hydride,sodium borohydride, aluminum hydride, gallium hydride, and aluminumborohydride.
 24. The method of claim 21, wherein M³ comprises Al and X²is Cl or Br.
 25. The method of claim 19, wherein A is Si.
 26. The methodof claim 19, wherein D is P or B.
 27. The method of claim 19, wherein Ris H, -A_(f)H_(2f+1) (where f is an integer≦4), or C₁-C₆ alkyl.
 28. Themethod of claim 19, wherein R¹ is phenyl or tolyl.
 29. The method ofclaim 19, wherein R⁴ is independently a substituted or non-substitutedcyclopentadienyl or fluorenyl ligand.
 30. The method of claim 29,wherein R⁴ is permethylcyclopentadienyl or fluorenyl.
 31. The method ofclaim 19, wherein R⁵ is independently a substituted or non-substitutedaryl.